The present invention relates to a sheet feeding mechanism for feeding cut sheets accommodated in a sheet cassette to, for example, an imaging apparatus.
There is an imaging apparatus such as a copying machine, printer, facsimile or the like, which prints on respective cut sheets of various sizes.
Usually in such an imaging apparatus, in order to facilitate printing on cut sheets of various sizes, removable sheet cassettes are used. One sheet cassette accommodates cut sheets of a predetermined size and is inserted into the apparatus. Accordingly, the image is formed on a cut sheet of the desired size by inserting the sheet cassette that has the required cut sheet.
In the imaging apparatus, a pick up roller is provided in order to pick up the cut sheet individually from the sheet cassette. Usually, the conventional apparatus is constructed such that the pick up roller contacts the uppermost one of the cut sheets when the sheet cassette has been completely inserted in the apparatus.
On the other hand, until the sheet cassette has been completely inserted in the apparatus, contact of the pick up roller with the uppermost cut sheet must be avoided for preventing the uppermost cut sheet from jamming by the pick up roller. Therefore, the conventional apparatus is constructed as follows, in order to avoid the above problem. Firstly, a path for guiding the sheet cassette is provided in the apparatus so that the pick up roller does not contact the uppermost cut sheet while the sheet cassette is being placed in the apparatus. Secondly, after placement of the sheet cassette has been completed, the sheet cassette is rocked upward toward the pick up roller. Thus, the sheet cassette has been completely inserted in the apparatus and the contact of the pick up roller with the uppermost cut sheet is accomplished.
In the construction as mentioned above, the conventional apparatus has the following problems. Firstly, since the space, where the cassette can be rocked upward, is needed, the apparatus has a larger size than is necessary. Secondly, the operator must place and rock the sheet cassette whenever he or she wants to change the paper size or replenish the cut sheets.